With ballasts for rail vehicles, cementing is effected particularly in the transition zones between soft and hard areas according to Applicant's German Patent Application P 39 41 141.9. According to Applicant's German Patent Application P 40 14 529.8, it may further be purposeful, particularly in curves, to increase the cross-sliding resistance of railway sleepers on ballast. According to Applicant's German Patent Application P 39 41 142.7, bottomings finer in grain on such ballasts are cemented using multi-component resins to increase sound absorption and/or cleanability of a railway track. In particular, cementing of pebbles and sand, with water permeability and porosity being retained, are performed to ensure rapid drainage of surface water, and thereby to reduce traffic noise even in rain.
In all these cases, as well as in similar fields of application for cementing porous granular material and bulk material using multi-component resins, it is required to apply a sufficient amount of said multi-component resins as uniformly as possible such that, at least in the upper region, the pasts are wetted over the total area, and adhesive bridges are formed at least at the contact points. Any excess amount of multi-component resin is to flow off downward and to coat further material there. By no means are the voids to be filled, as this would impede porosity of the cemented bulk material as well as its permeability for water and other liquids. Thus, the multi-component resins should not be too highly viscous and, if possible, not thixotropic. The setting reaction is to occur only after a sufficient depth of the bulk material layer is coated with the multi-component resin but not filled up to total volume. Since multi-component resins generally are very reactive substances possibly leading to irritation of skin and mucosae when processed, formation of spray mists should be suppressed or completely avoided. Moreover, processing in tunnels or in closed spaces should be performed without using solvents. In principle, this requirement also holds in open air since solvents evaporating immediately or subsequently result in an environmental burden to be avoided if ever possible. Nevertheless, the multi-component resins must be applicable rapidly, simply, and safely to keep material and wage expenses as low as possible.